Memory devices can include internal, semiconductor, integrated circuits in computers or other electronic devices. There are many different types of memory including random-access memory (RAM), read only memory (ROM), dynamic random access memory (DRAM), static RAM (SRAM), synchronous dynamic RAM (SDRAM), and flash memory.
Flash memory devices have developed into a popular source of non-volatile memory for a wide range of electronic applications. Flash memory devices typically use a one-transistor memory cell that allows for high memory densities, high reliability, and low power consumption. Common uses for flash memory include personal computers, personal digital assistants (PDAs), digital cameras, and cellular telephones. Program code and system data such as a basic input/output system (BIOS) are typically stored in flash memory devices for use in personal computer systems.
A typical erase operation holds the word lines of the memory block being erased at ground potential while the tub of the memory block is formed is biased at a high positive voltage. The high positive voltage can typically be in a range of 22-24V. The memory block is typically 64 pages of single level cell data and 128 pages of multilevel cell data where each page is page is typically comprised of 2048 bytes of data with 32 word lines.
The capacitance of the tub of the memory block being erased can typically be relatively high. The high capacitance makes it difficult for the charge pump to increase the voltage of the tub to the required high erase voltage. Therefore, a larger charge pump is used to produce the necessary high tub voltage, which often leads to larger die size. This goes against the trend by memory device manufacturers of reducing memory die size.
Additionally, the power consumption of the larger charge pump is high because of its size. Larger charge pumps are not as efficient as smaller charge pumps and, therefore, waste power more so than smaller pumps. The higher power consumption of the inefficient large charge pumps also goes against the current trend by memory manufacturers of reducing power requirements for memory devices.
For the reasons stated above, and for other reasons stated below that will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art to reduce the typical high erase voltage in a non-volatile memory device.